Sand is becoming New England coastal dwellers' most coveted and controversial commodity as they try to fortify beaches against rising seas and severe erosion caused by violent storms.

From Westerly, R.I., to Eliot, Maine, debates over who gets sand, who pays for it and where it comes from are fast becoming some of the region's most contentious oceanfront issues. In many cases, taxpayers are being asked to foot some of the bill for beach-rebuilding projects.

"It's called the sand wars,'' said S. Jeffress Williams, a coastal geologist and scientist emeritus with the United States Geological Survey in Woods Hole and the University of Hawaii. The disputes, happening across the coastal U.S., "are only going to get more intense," he said.

Among the seaside squabbles, some residents in Salisbury want $300,000 in state taxpayer dollars for sand to help protect private homes from the ocean's fury.

Winthrop Beach is poised to receive an estimated 20,000 truckloads of sand from Saugus as part of a massive beach replenishment and improvement project that is costing state taxpayers $26 million.

And in ocean-battered Nantucket and Plum Island, residents want to pay privately for sand to stand sentry against the encroaching ocean — but are running into regulators' opposition over how best to protect property.

For all the billions of grains of silica on and off New England's coastline, sand is maddeningly difficult — and expensive — to get. Fishermen and their regulators have opposed the mining of offshore sand because they worry it will harm sea life. Environmental officials say bulldozing it across beaches can accelerate erosion and harm bird nesting grounds. Mining and trucking sand from inland sources to beaches can be more than four times as expensive, damage roads and produce sand that is often darker and a different texture.

Meanwhile, large amounts of sand once deposited onto area beaches as a byproduct of federal navigational dredging are declining along with funding for those projects.

The stakes are rising with sea levels.

New England seas are rising at an annual rate three to four times faster than the global average. Scientists predict that seas here could rise 3 feet by the end of the century and we could see more powerful storms of the ilk of those in 2011 and 2012. The one-two punch of powerful storm surges atop higher seas is expected to mean more erosion and flooding — all of it farther inland.

Replenishing beaches is big business elsewhere along the Atlantic Coast, where long meandering ribbons of sand from New York to Florida have been fortified for decades to protect shore front homes and vacation destinations. New England beaches tend to be smaller and much of the coast is privately owned, so big projects never gained much political traction. There also is, environmentalists say, a leftover suspicion of mining anything from the sea that stretches back to oil exploration attempts in the early 1980s.

But as officials frown upon the new construction of seawalls because it can exacerbate erosion, sand is becoming increasingly valuable as the first line of defense against the ocean.

Record-keeping is poor on New England sand replenishment, although Massachusetts has begun to develop a database to track its use. Using that database and in interviews with coastal communities, the New England Center for Investigative Reporting conservatively estimates more than $40 million in federal, state and local funds have been spent to place sand on Massachusetts' public beaches in the last 10 years. That amount is minuscule compared to the billions being spent to protect and replenish beaches farther south in the wake of Sandy — yet coastal specialists say demand for sand is guaranteed to rise for both public and private beaches.

Massachusetts is now re-examining the possibility of mining sand offshore and a special commission on coastal erosion has been established by the state Legislature.

Many coastal dwellers and communities argue that the state and federal governments need to take care of beaches much the way they take care of roads. But others, often those farther away, say constantly replenishing beaches, many in front of second homes, with taxpayer dollars is a losing proposition.

"I don't think taxpayers have any idea what they are paying for,'' said Peter Shelley, senior counsel for the Conservation Law Foundation, a legal advocacy group. He said public dollars are needed to protect Boston's infrastructure to ensure the region's economic hub is protected, not "people's beach houses. These beach replenishment projects are temporary at best."

THE HUNT FOR SAND

The idea seemed simple more than a decade ago: Mine gravel and sand some eight miles off Winthrop's storm-battered beach and place it in front of a sea wall to act as the town's first defense against powerful waves.

But fishermen and their federal regulators opposed the sand mining, saying it would disturb essential habitat for cod. After years of controversy, it was decided that trucks would bring in the sand not from any ocean source, but from an abandoned highway project in Saugus. The price tag is close to three times the original planned cost.

The project — one of the longest and most controversial in the state over sand — has had a chilling effect, coastal community officials and engineers say.

"Massachusetts is one of the most restrictive states for sand mining,'' said John Ramsey, coastal engineer and co-owner of Applied Coastal Research and Engineering in Mashpee, which works with coastal communities on the Atlantic and Gulf coasts. He said fishing interests have prevented the conversation here but elsewhere "sand mining is accepted — and encouraged as a method of shore protection."

Massachusetts has permitted only a few private and public projects to take sand from offshore specifically for beach replenishment and pump it onto nearby beaches, according to a review of dozens of projects. One, for example, allows Orleans officials to take sand each year from flats about 500 feet from Skaket Beach.

Yet the rising demand for sand has the state re-examining offshore mining. The state is updating its ocean plan "to identify areas that have the least conflicts," said Bruce Carlisle, director of the state Office of Coastal Zone Management. He cautioned any sand mining would need to "be balanced with other interests" such as protecting fish habitat and other environmental and maritime concerns.

Some coastal experts are calling for a regional approach: Find pockets of sand offshore that everyone could mine. While Winthrop's offshore proposal became an environmental flashpoint, not every area needs to be.

"You could strategically select sand sources…and borrow appropriately to minimize environmental impact,'' said Bob Hamilton, a coastal engineer and vice president of the Woods Hole Group in Falmouth, an environmental consulting firm.

Historically, much of the sand deposited on area beaches was a byproduct — material dredged to clear navigational channels.

But large-scale navigation projects by the U.S. Army Corps of Engineers are declining in New England. In Massachusetts, for example, there were about six projects per year in the early and mid 2000s, according to the Corps. Excluding Superstorm Sandy work, there have been none in the last three years, according to Ed O'Donnell, chief of navigation for the Corps New England District. The region, with few deep ports and relatively small amounts of cargo traffic, does not compete well against other regions in the country for navigational projects, he said. So when a navigation project is planned — as one is now in the Maine town of Eliot to dredge the Piscataqua River — communities can line up to get sand.

Some communities, such as in Barnstable County, banded together with the state's help to buy a dredge that allows them to mine sand-clogged channels and inlets that can be as much as 70 percent below the market rate. But many other coastal communities do not have such options and must get sand elsewhere. Duxbury Beach Reservation Inc., a nonprofit, spent more than $1 million this year rebuilding dunes with imported quarry sand.

"We are always looking for sand,'' said Margaret Kearney, president of the reservation.

The fresh layered dunes and snow fencing in front of beach homes on Plum Island's southern end belie the ragged erosion from this year's February blizzard and March nor'easter. The storms toppled or forced the demolition of seven homes on the Newbury portion of the island.

The destruction intensified homeowners' long fight with state officials for the right to save their property.

Several homeowners were allowed by the state and Army Corps to take sand, called scraping, from the beach to place in front of homes last year right before Sandy as an emergency measure. Yet state and federal officials rarely approve beach scraping because it can harm bird and other wildlife habitat and even exacerbate erosion because it changes the contours of a beach. Now, a larger group of homeowners is expected to apply this year for beach scraping - setting up a possible showdown with regulators.

"We need to protect beaches,'' said Bob Connors, a Plum Island resident whose Newbury beachfront house is threatened by the sea. The beach provides "protection for roadways and other structures behind them. If we want to have beaches in Massachusetts we have to sustain them — it's just like painting a bridge," he said.

A few miles north on Salisbury Beach, Ray Champagne, head of the Salisbury Beach Betterment Association, agrees. Oceanfront owners spent upward of $5,000 each in the last year to recreate dunes in front of their homes taken by last year's storms. But the state beach in front of them remains low, raising fears the ocean may come in even faster this nor'easter season to overcome their dunes and flood homes. They want a $300,000 earmark — vetoed by Gov. Deval Patrick but overridden by the Legislature — to be used to put sand on the state beach, but in front of homes. So far, no decision has been made by the state where to put the sand.

"We don't like to have a neighbor that doesn't take care of their property,'' said Champagne.

The trials of Salisbury and Plum Island helped spark state Sen. Bruce Tarr, a Gloucester Republican, to sponsor legislation this year to create a special commission on coastal erosion to decide a critical question.

"Are we going to retreat or are we going to defend the coast?" Tarr asked. "And if we are going to defend, how are we going to do it?"

The New England Center for Investigative Reporting, www.necir.org, is a nonprofit investigative reporting newsroom based at Boston University and WGBH TV/radio and supported in part by New England news outlets. NECIR interns Michael Bottari and Alicia Juang helped research and prepare this report. Follow Beth Daley at @BethBDaley